.showimg {
    width: 500px;
    height: 300px;
    margin:  0 auto;
    position: relative;
}

.showimg img{
    width: 100%;
    height: 300px;
}

.btnj {
    width: 30px;
    height: 30px;
    line-height: 30px;
    text-align: center;
    position: absolute;
    border-radius: 50%;
    background-color: rgba(0,0,0,0.3);
    top: 50%;
    transform: translateY(-50%);
    color: white;
}

.prev {
    left:0
}

.next{
    right: 0;
}

.btn:hover {
    cursor: pointer;
    background-color: black;
}
